THREE-CSG handle group geometry resulted in no group

Questions
,
1

Hello there!
Found this

图片
图片1202×335 13.1 KB

The first one is a merged mesh with 10 material
After CSG subtract

CSG.toMesh(
    CSG.fromMesh(mergedMesh).subtract(CSG.fromMesh(sphere)),
    mergedMesh.matrix,
    materialArray
)

图片
图片1138×283 9.7 KB

Any solution based on merge mesh will be great !